function Circle(x, y, r) {
	this.x = x;
	this.y = y;
	this.r = r;
}

new Circle(0, 0, 0);

Circle.prototype.pi = 3.14159;

function Circle_circumference() {
	return 2 * this.pi * this.r;
}
Circle.prototype.circumference = Circle_circumference;

Circle.prototype.area = function() {
	return this.pi * this.r * this.r;
};

var c = new Circle(0.0, 0.0, 1.0);
var a = c.area();
var p = c.circumference();

//------//
String.prototype.endsWith = function(c) {
	return (c == this.charAt(this.length - 1));
};

var message = "hello world";
message.endsWith('h');
message.endsWith('d');